This invention relates to a numerical control information generating apparatus which generates a numerical control information.
Nowadays, there has been widely used a numerical control information generating apparatus capable of inputting data in an interactive manner by an operator upon generating numerical control information to be inputted to a numerically controlled machine tool. If the numerical control information generating apparatus as such is provided with a kind of material to be machined, a before-machining shape, an after-machining shape, etc., the numerical control information generating apparatus automatically determines a machining method (machining region, cutting direction, cutting tool, cutting condition, sequence of operations, etc.,) to generate the numerical control information.
FIGS. 1A and 1B are block diagrams showing an embodiment of a conventional numerical control information generating apparatus in a numerically controlled lathe. In this configuration, a before-machining shape SA, as well as an after-machining shape SB inputted through an operation control panel 1 such as a keyboard or the like by an operator are read in a data input section 2 to be analyzed, and then are stored respectively in a before-machining shape storing section 3 and an after-machining shape storing section 4. The after-machining shape SB being stored in the after-machining shape storing section 4 is read into an after-machining shape-portion classifying section 5 to be decomposed into various pattern elements. The decomposed pattern elements are classified properly according to the portion to be machined, or the cutting direction, and the classified data are read into a feature extracting section 6 as an after-machining-shape classification data SC.
The after-machining-shape classification data SC which the feature extraction section 6 has read out of the after-machining shape-portion classifying section 5 are compared with the before-machining shape SA which the feature extracting section 6 has read out of the before-machining shape storing section 3. From this comparison, shape features SD which are used as factors to determine the machining method, is extracted to be stored in a feature temporary memory 7. Subsequently, the shape features SD loaded into a feature judging section 8 are compared therein with a machining method judgement parameters SE which are read out of a parameter storing section 19 through a parameter temporary memory 20 by the feature judgement section 8. The resultant is outputted as feature comparison data SF to be transmitted to a machining after-machining determining section 9 and a machining method SG is determined. This machining method SG is read into a machining step data generating section 10, and analyzed to generate machining step data SH for each operation step including the cutting shape, the cutting tool, the cutting condition, the sequence of cutting and the like.
The machining step data SH generated in the machining step data generating section 10, the before-machining shape SA stored in the before-machining shape storing section 3 as well as the after-machining shape SB stored in the after-machining shape storing section 4 are read in by a display control section 11 to be transformed into display data SI. The transformed data is adapted to be displayed via a display data output section 12 on a display device 13.
On the other hand, the machining step data SH generated in the machining step data generating section 10 is fed into a numerical control information generating section 14 to be coded, and the coded data are outputted as a numerical control information SJ via a numerical control information output section 15 to a magnetic tape 16, a floppy disc 17, a communication signal 18 or the like.
FIG. 2 is a flow chart showing an operational example of the main part of the conventional numerical control information generating apparatus described above. At first, the data input section 2 stores the before-machining shape SA and the after-machining shape SB which are inputted through the operation control panel 1, respectively into the before-machining shape storing section 3 and the after-machining shape storing section 4 (Step S101). The after-machining shape-portion classifying section 5 loads the after-machining shape SB stored in the after-machining shape storing section 4 to be decomposed into pattern elements. Then, a judgement is made as to whether the machining portion suitable for each pattern element belongs to the inner diameter portion or the outer diameter portion, and further another judgement is made as to whether the machining direction suitable for each pattern element is forward or backward. As a result, each pattern element is classified into one of four machining kinds such as inner diameter forward machining, inner diameter backward machining, outer diameter forward machining and outer diameter backward machining, to generate the after-machining-shape classification data SC (Step S102).
Next to this, the feature extracting section 6 extracts among a series of pattern elements which forms the after-machining shape SB, features of pattern element shapes which affect and determine the machining methods necessary for the pattern elements to be machined. The extracted features are stored as the shape features SD in the feature temporary memory 7 (Step S103). The feature judging section 8 reads out the machining method judgement parameters SE stored in the parameter storing section 19 via the parameter temporary memory 20 (Step S104), and compares them with the shape features SD stored in the feature temporary 7 to generate the feature comparison data SF. Subsequently, the machining method determining section 9 determines the machining methods based on the feature comparison data SF (Step S105), whereby all procedures are completed.
In a case where a machining method is determined, for example, according to the before-machining shape SA and the after-machining shape SB as shown in FIG. 3, at first, a point at which the Z-coordinate value is minimum and the X-coordinate value is minimized in the pattern elements forming the after-machining shape SB is defined to be a search starting point P0. Then, the series of the pattern elements (P0, P1, . . . , P11, e1, e2, . . . , e12) which forms the after-machining shape SB, is sought sequentially from the search starting point P0, to determine an inner diameter-outer diameter dividing point P5 at which the Z-coordinate value is maximum and the X-coordinate value is minimized, an inner diameter forward/backward dividing point P2 at which the X-coordinate value is minimum and the Z-coordinate value is minimized, and an outer diameter forward/backward dividing point P9 at which the X-coordinate value is maximum and the Z-coordinate value is minimized.
Next, the pattern elements e1 through e12 are divided into four groups, that is, the pattern elements (e1 and e2) which are located between the search starting point P0 and the inner diameter forward/backward dividing point P2; the pattern elements (e3, e4 and e5) which are located between the inner diameter forward/backward dividing point P2 and the inner diameter/outer diameter dividing point P5; the pattern elements (e7, e8 and e9) which are located between the inner diameter/outer diameter dividing point P 5 and the outer diameter forward/backward dividing point P9; and the pattern elements (e10, e11 and e12) which are located between the outer diameter forward/backward dividing point P9 and the search starting point P0. The divided four group of pattern elements are classified respectively to be subjected to the inner diameter backward direction machining (for the elements e1 and e2), the inner diameter forward direction machining (for the elements e3, e4 and e5), the outer diameter forward direction machining (e6, e7, e8 and e9), and the outer diameter backward direction machining (e10, e11 and e12). In FIG. 3, the pattern elements needed to be subjected to the cutting process are the pattern elements e7 and e8, so that the machining method to be practiced is determined to be the outer diameter forward direction machining.
Moreover, for the pattern elements which are needed to be machined, an angle A made between the pattern element and the Z-axis, a pattern element length L in the direction of the X-axis, and a cutting stock D are extracted as the shape features SD which are determining factors for the machining method. These extracted features are compared respectively with the machining method judgement parameters SE stored in advance, consisting of a limiting value PA of the angle, a limiting value PL of length in the X-axis direction, and a limiting value PD of the cutting stock. Here, if the compared resultant satisfies the all of the following equations (1), (2) and (3), the machining method for the pattern element in question is determined as to be a face machining, and if any of the three equations (1) to (3) is not satisfied, the machining method for the pattern element is determined as to be a longitudinal machining. EQU A.gtoreq.PA (1) EQU L&gt;PL (2) EQU D.ltoreq.PD (3)
In the conventional numerical control information generating apparatus detailed above, in judging whether the machining method necessary to obtain an after-machining shape from a before-machining shape is composed of a face machining or a longitudinal machining, the machining method is judged separately for each pattern element, so that the machining methods may not be properly optimized as compared with the case where the all machining regions are considered as a whole. In a case where, for example, a machining method is determined for an element having a before-machining shape and an after-machining shape as shown in FIG. 4, if the length L64 of the X-axis direction in the pattern element e64, and the length L66 of the X-axis direction in the pattern element e66 satisfy the following equations (4) and (5) respectively, the pattern element e64 as well as the pattern element e66 are determined to be subjected to the longitudinal machining. EQU L64.ltoreq.PL (4) EQU L66.ltoreq.PL (5)
However, when a skilled machining operator considers the machining method assuming the machining region R6 as one pattern element, the operator usually adopts a face machining to machine the machining region R6. Accordingly, in order to obtain the optimum machining method for each pattern element, the operator must manage to change or amend the generated operation step data and the numerical control information based on the determined machining method, thus giving rise to a difficulty in this system.